Express Queues/Topics allows high throughput and low latency of messages. This is achieved by the queuing mechanism caching the received message directly to memory first. If the message is not consumed within a few seconds, it will be written to persistent storage.

If a publisher sends any crucial messages to the queue that must not be lost, the publisher must set the ForcePersistence property to true. This will force the queuing mechanism to immediately persist the message to store.